Trajectory-based control under ZMP constraint for the 3D biped walking via fuzzy control

In this study, a fuzzy control policy is presented for dynamic walking of a biped robot that is modeled as a simulated five-link biped robot. Due to complex ground contact models, it is difficult to precisely model its dynamics. Besides, a spring/damper ground model and a simplified inverted pendulum model are presented to represent the ground contact relation and the approximated model of biped robots as well. Moreover, Finite State Machine (FSM) is utilized to decompose a cycle of walking gait. Under zero moment point (ZMP) constraint, each joint follows desired trajectories in each state that are generated by quintic spline curve through the model free controller (i.e., fuzzy control). In addition, its robustness is investigated by imposing pulse perturbation on torso for some directions. The results are demonstrated in simulations as well as animation and then the proposed controller is compared with a PID controller as well.